Big thanks to Jon, TJ, TVo and Jason for a 6-hour effort.

Today was a big day aligning things on HAM4. We got the main alignment laser set up using the gooseneck mounts and corner cubes. We got the new 4" HWSX STEER M1 mirror mount installed, replacing the old mount and shifting the pedestal in +Y direction by approximately 20mm. 

Unfortunately, we ran into two problems with the DCBS mirror mount replacement. Firstly, the pedestals were machined for 2" Sisikyou mounts (which we were to recover from the HAM IS OPLEVs). However, these turned out to be a different (non-Siskiyou) mirror mount which placed the optic about 7-10mm higher than desired. Additionally, it turns out that the X and Y HWS arms are are slightly different beam heights. The result of these two issues put the Y-arm DCBS about 10mm higher (borderline usable) than desired and the X-arm was about 20mm higher (not usable). We're going to have to remachine them. I'll post images and full details tomorrow.

Good news: the Y-ARM DCBS can now easily tilt its reflection down cleanly into the HWS SCRAPER baffle. Also, the alignment of the DCBS can be done in future with a simple laser on confined to HAM4, rather than the whole ITMY, BS, SR3, PR3 procedure we did today.